Well: osteo arthritis is natural in that it is gradual wear and tear of the joints, because humans evolved upright

. OTC pain relief should help, as would checking your seating and sleeping positions. Good quality foot wear is important. Gentle exercise; learning to kneel rather than bending over can all help as we age. Whilst 'incurable' it isn't the same as a cancer that isn't curable .
Many years ago I woke in the early hours with excruciating pain so deep in my R thighs that I couldn't scream out loud. Good job really as we were in B&B at the time! I worked out eventually that it was due to my bending over low antique cabinets at fairs, therefore pulling my muscles. I also have bilateral bursitis: if I did the exercises recommended by the physio. that might ease too!
U could begin with pain relief prior to doing anything such as mowing the lawn. We are able to self refer to physio. these days so it might be worth while getting your gait checked as well as your posture. I know that I am leaning forwards more so have to remind myself to 'get upright!'.
Rheumatoid is different.
As oestrogen levels drop muscles may become lax = aches and pains so HRT may help. Pain in the groin may be related to the hip area. Pain over the 'hips' is often due to back strain or wear and tear.
Don't despair. Hopefully some1 will be along with advice about the kind of HRT which may help.